The present invention relates to an interface apparatus, a control method therefor, and an information-recording medium; particularly, the invention relates to an interface apparatus that allows data and commands to be transferred between two hosts so as to serve as an interface for communication therebetween, and shifts to a power-saving state as and when required, thereby allowing power consumption to be reduced, and concurrently, that controls transition to the power-saving state in accordance with the hosts to allow data and commands to be transferred at a high speed; a control method for the interface apparatus; and an information-recording medium for recording a program for controlling the interface apparatus.
As an interface apparatus that serves as an interface for transmission of data and commands between two hosts, an interface apparatus in which one of the hosts is a computer and the other one of the hosts is a printer, an interface apparatus that serves as a hub for connecting multiple hosts, for example, for connecting a computer and a computer, and other various types of interface apparatus are provided.
For sending data and commands from a computer to a printer, various cases where they are sent via various types of paths. For example, there are cases where they are sent via a parallel port and an RS-232C port that are included in a computer and where they are sent via a bus widely used in recent years, such as that according to USB (Universal Serial Bus) or according to IEEE (Institute of Electrical and Electronic Engineers) 1394.
Thus, the type of connector differs in various ways depending on standards. The connection status on the side of computers may be variable; however, hardware of printers is preferably common. In this situation, an interface apparatus first receives data and commands to be sent through the aforementioned various types of connections and performs voltage-conversion, impedance-matching, buffering of the sent data and commands, and interpretation and filtering thereof; and thereafter, it converts them to, for example, the RS-232C format, and outputs them.
Thus, by exchanging the interface apparatus, a single printer can be used to meet various conditions. That is, depending on combination of the interface apparatus and the printer, the printer that corresponds to various types of connectors can be provided. Thereby, printers can be mass-produced, thereby allowing costs required for the entire printing unit to be reduced.
On the other hand, for the interface apparatus, reduction in power consumption is preferable in view of operation costs and environment protection. For these reasons, many computers and printers are designed to shift to a power-saving state independently of each other while they are not used for a predetermined period of time.
Also, in the described type of the interface apparatus, the reduction in the power consumption is preferable in view of operation costs and environment protection. As power-saving modes for reducing power consumption, there are methods such as that a clock level of a CPU (central processing unit) that controls an interface apparatus is lowered, and intermittent operations are performed, in which the power-saving modes can be varied by specifying various parameters for the lowering level of the clock, the intermittent-operation rate, and the like.
However, the conventional interface apparatus arise problems as described below.
That is, while a first host such as a computer and a second host such as a printer have been developed so as to meet the power-saving requirements and so as to reduce power consumption, almost no development has been implemented for the interface apparatus for the power-saving requirements. Therefore, problems arise in that operation costs increase. These problems are not preferable also in view of the environment protection.
Also, since the two hosts shift to the power-saving state independently of each other, only one of the hosts is used to control the entire power-saving function of the interface apparatus. This is not practical, because the power-saving status in the other one of the hosts must be considered.
Therefore, a preferable interface apparatus is such that it recognizes the status of the two hosts, and concurrently, providing the power-saving function according to instructions from the hosts.
Also, a desired power-saving mode differs in a case where it is implemented in a printer that has a high power-supplying capacity and in a case where it is implemented in a printer that has a lower power-supplying capacity. However, in the conventional interface apparatus, no measures are taken for the power-saving mode that differs according to the difference in the power-supplying capacity. Therefore, problems arise in that power consumption cannot be sufficiently reduced.
The present invention is made to solve the above-described problems, and an object thereof is to provide an interface apparatus that allows data and commands to be transferred between two hosts so as to serve as an interface for communication therebetween, and shifts to a power-saving state as and when required, thereby allowing power consumption to be reduced, and concurrently, that controls transition to the power-saving state in accordance with the hosts to allow data and commands to be transferred at a high speed; a control method for the interface apparatus; and an information-recording medium for recording a program for controlling the interface apparatus.
Also, another object of the present invention is to provide an interface apparatus that receives power required for operation from a connected host, and also, that receives information required for saving power from the host so as to independently determine a power-saving mode; a control method for the interface apparatus; and an information-recording medium for recording a program for controlling the interface apparatus.
In order to achieve the aforementioned objects, an interface apparatus of the present invention has a receiving means for receiving data from a first host unit and a sending means for sending the data received by the receiving means from the first host unit to a second host unit, characterized by comprising a wait-state selecting means for selecting a predetermined wait state from a plurality of wait states according to operation of one of the receiving means and the sending means.
In this case, it is preferable that the wait-state selecting means comprise a control-command detecting means for interpreting the data received from the first host unit to extract control commands, a normal-wait-state selecting means for selecting a normal-wait state when the data was found by the control-command detecting means to be data other than a control command, a command-wait-state selecting means for selecting a command-wait state when the data was found to be a control command according to the control-command detecting means, a command-completion recognizing means for recognizing completion of a control command extracted by the control-command detecting means, a command-wait-state resetting means for resetting the command-wait state and selecting the normal-wait state when completion of the control command is recognized according to the command-completion recognizing means, a first clocking means for clocking time passed after the normal-wait state is selected, and a power-saving-wait-state selecting means for resetting the normal-wait state and selecting a power-saving wait state when a predetermined time was found to have been passed after the normal-wait state is selected according to the first clocking means.
According to the described characteristics, the interface apparatus that allows data and commands to be transferred between two hosts so as to serve as an interface for communication therebetween, and shifts to a power-saving state as and when required, thereby allowing power consumption to be reduced, and concurrently, that does not shift to the power-saving wait state during command reception, thereby allowing commands to be transferred at a high speed.
Also, in the above, it is preferable that the interface apparatus further comprise a first notifying means for posting a notification to the first host unit when the power-saving wait state is selected by the power-saving-wait-state selecting means.
The above characteristics allow the provision of the interface apparatus wherein the first host can recognize a current status of the interface apparatus.
Also, in the above, it is preferable that the interface apparatus further comprise second notifying means for posting a notification to the second host unit when the power-saving wait state is selected by the power-saving-wait-state selecting means. These characteristics allow the provision of the interface apparatus wherein the second host can recognize a current status of the interface apparatus. Particularly, according to the aforementioned notification, the second host can independently shift to the power-saving wait state.
Also, in the above, it is preferable that the wait-state selecting means comprise a second clocking means for clocking time passed after the power-saving wait state is selected, and a power-saving-wait-state resetting means for resetting the power-saving wait state and selecting the normal-wait state when a predetermined time was found to have been passed after the power-saving wait state is selected according to the second clocking means. According to these characteristics, the interface apparatus that repeats the power-saving state and the normal-wait state at a predetermined cycle so as to response to data and commands at a high speed can be provided.
Also, in the above, it is preferable that the interface apparatus further comprise a third notification means for posting a notification to the-first host unit when the power-saving wait state is reset by the power-saving-wait-state resetting means. These characteristics allow the provision of the interface apparatus wherein the first host can recognize a current status of the interface apparatus.
Also, in the above, it is preferable that the interface apparatus comprise a fourth notification means for posting a notification to the second host unit when the power-saving wait state is reset by the power-saving-wait-state resetting means. These characteristics allow the provision of the interface apparatus wherein the second host can recognize a current status of the interface apparatus.
Also, in the above, it is preferable that the interface apparatus comprise a control-command interpreting means for interpreting a control command detected by the control-command detecting means, and a power-saving-wait-state inhibiting means for inhibiting selection of the power-saving wait state by the power-saving-wait-state selecting means when a predetermined control command is interpreted by the control-command interpreting means. These characteristics allows the provision of the interface apparatus that can control transition to the power-saving wait state via the first host and that inhibits the transition, thereby allowing data and commands to be transferred at a high speed.
Also, the interface apparatus of the present invention is characterized by further comprising a power-supplying means that has a plurality of power-saving modes and that supplies power supplied from the first host unit to the interface apparatus, wherein the wait-state selecting means comprises power-information receiving means for receiving power-supplying capacity information on the first host unit via the sending and receiving means, and a first determining means for determining the power-saving mode employed by the power-supplying means according to the power-supplying capacity information on the first host unit, which was received from the power-information receiving means.
The above characteristics allows the provision of the interface apparatus that receives power required for operation from the connected host and obtains information required for saving power from the host, thereby being capable of independently determining the power-saving mode.
In the above, it is preferable that the wait-state selecting means comprise a storing means for storing a pair of device-type-name information on the first host and the power-supplying capacity information on the first host; the power-supplying capacity information on the host, which is received from the power-information receiving means, includes the device-type-name information on the first host; and the determining means searches the storing means on the key of data of the device-type-name information on the host, which was received from the power-information receiving means and determines the power-saving mode employed by the power-supplying means according to the obtained power-supplying capacity information on the first host. These characteristics allows the provision of the interface apparatus that can determine a mode most suitable to the power-supplying capacity of a host even in a case where the host has no function for sending power-supplying capacity information while it can send the device-type name.
Also, in the above, it is preferable that the wait-state selecting means comprise a second determining means for recognizing variation in either one of voltage and current or the both of power supplied by the first host, thereby determining the power-saving mode employed by the power-supplying means. These characteristics allows the provision of the interface apparatus that experimentally measures the power-supplying capacity of a host even in a case where the host can not send the power-supplying capacity information nor can it send information on the device-type name, thereby determining the power-saving mode most suitable to the power-supplying capacity of the host.
Also, the present invention is very effective as a control method for an interface apparatus. It can be understood when it is considered by replacing the described configuration of the interface apparatus with the control method. In addition, when the control method can be implemented using a computer, an information-storing medium containing a control program therefor is also included in the scope of the present invention. In this case, it is preferable that the information-storing medium be one of a compact disk, a floppy disk, a hard disk, an optical magnetic disk, a digital videodisk, and a magnetic tape.
The invention of the information-storing medium allows the information-storing medium containing the program to be distributed or sold independently of the interface apparatus. By execution of the program in the interface apparatus, the interface apparatus and the control method therefore according to the present invention are realized.
Particularly, any one of the compact disk (so-called a CD-ROM), the floppy disk, the optical magnetic disk, a digital videodisk (so-called a DVD-ROM), and a magnetic tape may be employed as the information-storing medium containing the program. Using one of these information-storing medium, these programs can be installed in existing interface apparatuss.
In addition, these programs can be registered at a WWW (World Wide Web) site so as to allow users to download and install them on existing interface apparatuss. These embodiments are also included in the technical scope of the present invention.
In the above and hereinbelow, a printer as a host and a computer as another host are individually employed and described. However, other electronic information apparatuses can be easily employed as hosts, and embodiments so arranged are also included in the technical scope of the present invention.
Also, the interface apparatus of the present invention can be applied to a network hub, a modem, or the like that serve as an interface for multiple units such as computer. Embodiments so arranged are also included in the technical scope of the present invention.
Furthermore, an embodiment that can be considered may be such that, between a printer and an interface board to be equipped with the printer, the interface board supplies power to the printer. In this case, the printer corresponds to the xe2x80x9cinterface apparatusxe2x80x9d, and the interface board corresponds to the xe2x80x9chostxe2x80x9d. An embodiment so arranged is also included in the technical scope of the present invention.